The present invention refers to a reflector for a vehicle headlight of the complex type, i.e. formed of a plurality of sectors oriented so as to permit the illumination of the surrounding space according to a predetermined light distribution.
Stylistic and performance requirements have always pushed the motor vehicle industry towards the use of headlights of reduced dimensions, with a smooth transparent element and complex reflecting surfaces. The principal problems in the designing of a reflector of this type are the limitation of dazzle in the dipped light beam, and the control of the light beam for the formation of the distribution of illumination according to the regulations. As may be seen from FIG. 1, according to the European regulations, the shape of the dipped light beam must be such as to form on a plane located at a specific distance from the headlight a light distribution which exhibits an abrupt variation of illuminance in the vertical direction at the horizontal axis, or axis x, located at the same height as the optical axis of the reflector. Such a discontinuity, known as cut-off, is necessary in order to guarantee a maximum value of illuminance immediately below the horizontal line and an almost zero illuminance value immediately above said line.
The angle of spread (or divergence) of the light beam reflected by each point of the reflector depends on the dimension of the virtual source at that point and on the distance between the source and the point on the reflector. In particular, it is important to consider the vertical angle of spread θ, or the angle of spread in the direction perpendicular to the plane of the road.
In order to obtain a predetermined light distribution, for example of the type described above, the conventional reflectors have a surface sub-divided into a plurality of facets for directing the light beam from a light source into predetermined zones of the distribution. A reflector for headlights of this type is known for example from U.S. Pat. No. 6,007,224. That patent describes a method for producing the reflector which provides for the arrangement of a plurality of facets of the reflector, the shape of which is established beforehand, to form a desired image of the source. The said patent further provides for the facets furthest from the light source to be intended to provide light to a region with greater light intensity of the light distribution generated, and for the facets closest to the light source to be intended to provide light to the regions of lesser light intensity of the light distribution.